English

Y is a least fixed point combinator

Logic 2025-04-29 v1

Abstract

The theory of recursive functions is related in a well-known way to the notion of *least fixed points*, by endowing a set of partial functions with an ordering in terms of their domain of definition. When terms in the pure lambda-calculus are considered as partial functions on the set of reduced lambda-terms, they inherit such a partial order. We prove that Curry's well-known fixed point combinator Y produces least fixed points with respect to this partial order.

Keywords

Cite

@article{arxiv.2504.19379,
  title  = {Y is a least fixed point combinator},
  author = {Joseph Helfer},
  journal= {arXiv preprint arXiv:2504.19379},
  year   = {2025}
}
R2 v1 2026-06-28T23:13:07.518Z